Thrombotic complications associated with early and late nonadherence to dual antiplatelet therapy

This study sought to assess the frequency and clinical impact of dual antiplatelet therapy (DAPT) nonadherence.

There are limited data on the impact of DAPT nonadherence during the first year after a second-generation drug-eluting stent placement.

After successful Endeavor zotarolimus-eluting stent implantation, 2,265 patients were enrolled in a registry with limited exclusions and monitored during 12 months of prescribed DAPT. Predictors of any nonadherence (ANA) at 6 months were analyzed by multivariable analysis, and the association between ANA at 6 or 12 months with the endpoints of death, myocardial infarction, and stent thrombosis was assessed.

The study population included 30% female patients, 34% with diabetes and 36% with acute coronary syndromes. ANA occurred in 208 patients (9.6%) before 6 months and 378 patients (18.5%) before 1 year. Major bleeding (odds ratio [OR]: 12.83, 95% confidence interval [CI]: 7.55 to 21.80, p < 0.001) was the only predictor of ANA at 6 months. In time-dependent analyses, ANA before 6 months was associated with an increased risk of death or myocardial infarction (7.6% vs. 3.0%, p < 0.001) and a numerical increase in stent thrombosis (2.0% vs. 0.9%, p = 0.12). After adjustment for baseline differences, ANA within 6 months remained associated with death or MI (OR: 1.95, 95% CI: 1.02 to 3.75). ANA occurring after 6 months did not increase the risk of subsequent ischemic events.

DAPT ANA occurs frequently and is associated with increased risk for thrombotic complications if it occurs within the first 6 months. Major bleeding was a significant correlate of DAPT ANA within 6 months. (EDUCATE: The MEDTRONIC Endeavor Drug Eluting Stenting: Understanding Care, Antiplatelet Agents and Thrombotic Events; NCT01069003).